Guide to writing abc for abc2midi
---------------------------------
The defining document for abc is the abc version 1.6 specification which can
be found at http://www.gre.ac.uk/~c.walshaw/abc2mtex/abc.txt . This document
is a description of abc as interpreted by abc2midi.
An abc tune consists of a header followed by a body. Each line in the
header is a different field starting with a letter immediately followed
by : and then the text of the field. The body of the tune contains lines
of music, though it may also contain certain fields. The end of the tune is
marked by a blank line (so blank lines cannot appear within the tune header
or body).
Comments are allowed in both the header and the body. A comment starts
with a % sign and continues to the end of the line. A comment may be on
a line of its own or at the end of a line of abc.
The header should look something like this :
X:1
T:The Rose Tree
M:4/4
L:1/8
Q:1/4=120
K:G
X: is the reference number (each tune in a file should have a unique reference
number). T: is the title of the tune, M: is the time signature, L: is the
default note length and K: is the key signature. Q: is the tempo field. In
the above example the tempo is given as 120 quarter-notes per minute. X:
must be the first field and K: must be the last field in the header.
It is advisable to write the fields M:, L: and Q: in that order. The
reason for this is that M: sets up a default note length which L:
over-rides and the tempo field Q: can be written in other forms that
depend on default note length. This order makes the meaning clear and
unambiguous.
Other fields may also appear in the header. Common ones are C: composer
of the tune, D: discography, H: history of the tune, S: source, N: notes,
Z: transcription note, A: area from which the tune comes, B: book
and R: rhythm.
The K: is made up of a base note A-G possibly followed by b for flat or
# for sharp. This specifies a major key. A minor key can be specified
by adding an m while Mixolydian and Dorian modes can be specified by adding
Mix and Dor respectively e.g.
K:Eb
K:EDor
K:EbDor
The following table relates the number of sharps or flats you see on the
stave to what is in the K: field :
7 sharps: C# A#m G#Mix D#Dor
6 sharps: F# D#m C#Mix G#Dor
5 sharps: B G#m F#Mix C#Dor
4 sharps: E C#m BMix F#Dor
3 sharps: A F#m EMix BDor
2 sharps: D Bm AMix EDor HP Hp
1 sharp : G Em DMix ADor
0 sharps: C Am GMix DDor
1 flat : F Dm CMix GDor
2 flats : Bb Gm FMix CDor
3 flats : Eb Cm BbMix FDor
4 flats : Ab Fm EbMix BbDor
5 flats : Db Bbm AbMix EbDor
6 flats : Gb Ebm DbMix AbDor
7 flats : Cb Abm GbMix DbDor
As an extension, abc2midi also recognizes "Maj" for Major "Min" for Minor,
"Phr" for Phrygian, "Lyd" for Lydian, "Aeo" for Aeolian and "Loc" for
Locrian. Thus CMaj, EPhr, FLyd, AAeo and BLoc will all generate a stave with
no sharps or flats. If you use one of these modes in the key signature, it is
recommended that you add a comment giving the number of sharps or flats for
the benefit of other people who may not be familiar with modes. e.g.
K: DLoc % 3 flats
The key signature may be followed by modifiers. A modifier consists of ^^, ^
=, _ or __ followed by a-g. As an example, ^a means every a should be played
sharp unless otherwise marked in the music. This over-rides whatever has been
set by the key signature. e.g.
K: C ^a
The Body of the Tune
--------------------
Following the header is the tune. This is a textual notation for the things
you might see on a stave :
Notes:
A note consists of a pitch specifier followed by a length. Available pitch
specifiers are :
C, D, E, F, G, A, B, C D E F G A B c d e f g a b c' d' e' f' g' a' b'
This covers 4 octaves. abc2midi allows lower octaves to be reached by
adding extra , characters and higher octaves to be reached by adding
extra ' characters. However, this is not standard abc and may not be
supported by other abc utilities.
You can raise or lower the pitch specifier a semitone by preceding it with
^ or _ respectively. The key signature and preceding sharps, flats and
barlines modify the default pitch in the same way as on a stave. Preceding
a note with = generates natural pitch and ^^ and __ can be used for double
sharp and double flat respectively.
The length is in general specified by a fraction following the pitch
specifier. However, the notation is made more concise by allowing much
of the fraction to be omitted.
C - selects a note of 1 default note length.
C2 - selects a note of 2 default note lengths.
C/2 - selects a note of 1/2 default note length.
C3/4 - selects a note of 3/4 default note length.
No space is allowed within a note, but space may be used to separate
notes in the tune.
Rests are written by using 'z' as the pitch specifier.
z3 - a rest of 3 default lengths.
Placing a dot before a note causes it to be played staccato.
.e
Combining notes
Three notes of the same length can be turned into a triplet by prefixing
them with (3. This has the effect of multiplying the note lengths by 2/3.
A chord can be represented by bracketting the notes together within [ and
] e.g. [a2e2]. An older notation which is also supported is to use + symbols
e.g. +a2e2+. The - symbol can be used to tie together notes of the same
pitch e.g. a2-a; this is equivalent to a3.
From version 1.4 of abc2midi, the support of tuples and chords is
extended to include general tuple notation (p:q:r , [ and ] for chords
and a more flexible system of interpreting chords.
(p:q:r means play the next r notes at q/p of their notated value. Thus
(3:2:3 is equivalent to an ordinary triplet (3 .
It is possible to have notes of different lengths within a chord
e.g. [ab2] . The length of the first note (or rest) in a chord is
taken as the time before the next note is played. The same effect can be
achieved using tied notes e.g. [ab2] c is equivalent to [ab-] [bc].
To resolve possible ambiguity, a tie sign is always assumed to belong to
the immediately previous note.
A run of 2 or more different notes may be grouped together in a slur.
This usually means that the notes are to be played together as smoothly as
possible. In typeset music, a slur looks very similar to a tie, but in
abc, ( marks the start of a slur and ) marks the end. e.g. (ABc) .
abc2midi recognizes slurs, but they have no effect on the MIDI generated.
Barlines :
| is an ordinary barline
|| is a double barline
:| is "repeat last section".
|: is "repeat next section".
:: is "repeat last and next sections".
|1 or |[1 or | [1 is "first repeat ending".
:|2 or :|[2 or :| [2 is "second repeat ending".
|] and [| are variants of ||.
If |1 and :|2 are used, the end of the second repeat should finish with
|| or |:, not :| or :: . abc2midi will try to fix up things if you miss
out a start repeat. Where a tune starts with an anacrusis, abc2midi will
always fix a repeat to start at the anacrusis rather than the first
barline.
Rhythm field and Broken Rhythm Notation
---------------------------------------
R:hornpipe causes notes written in straight time to be played in dotted
time. The symbol > can be used to achieve a similar effect.
a>b is notated as a3/2b/2 but played as a4/3b2/3.
The symbols < >> << >>> <<< have similar meanings:
a<b is notated as a/2b3/2 but played as a2/3b4/3.
a>>b is notated and played as a7/4b/4.
a<<b is notated and played as a/4b7/4.
a>>>b is notated and played as a15/8b/8.
a<<<b is notated and played as a/8b15/8.
abc2midi may refuse to apply the dotted time symbol if a and b are
not simple notes. In this case, the note lengths should be written
directly.
Guitar chords :
Anything in quotes is a guitar chord e.g.
"A" "Gm" "B7" "Bm7" "D#aug" "Bbdim7"
Guitar chords must use upper case A-G followed by optional # or b, then
the name of a chord type e.g. "m", "aug", "7". abc2midi currently
recognizes the following chord names :
m, 7, m7, maj7, M7, 6, m6, aug, +, aug7, dim, dim7, 9, m9, maj9, M9,
11, dim9, sus, sus9, 7sus4, 7sus9, 5
You can also add your own; see the %%MIDI chordname command below.
abc2midi automatically generates an accompaniment from the guitar chords.
There are a number of default chord/fundamental rhythms for common time
signatures which this uses, or you can set up your own.
Lower case a-g followed by optional # or b will generate a single note,
the fundamental, only.
This notation has been extended so that finger numbers "1" "2" "3",
"4" or "5" are allowed. abc2midi ignores these, but a typesetting
program might support them.
Another extension is to allow musical instructions to appear in exclamation
marks e.g. !pizzicato! abc2midi currently supports the following :
!ppp! !pp! !p! !mp! !mf! !f! !ff! !fff!
Default volume is equivalent to !f!. In both the " " and ! ! fields,
abc2midi allows multiple terms separated by semi-colons e.g. "Am;1".
A line of music may contain any number of notes, barlines and guitar
chords. Spaces may be used to separate these.
Some abc fields may appear within the body of the abc tune :
K: - change key
L: - change default note length
M: - change meter
Q: - change tempo
P: - part label
V: - voice label
w: - words to be matched syllable by syllable to notes
Each field must be on a line by itself.
Part Notation
-------------
A part label must be a single character in the range A - Z. e.g.
P:A
A parts specifier in the header can be used to define the MIDI output as
some combination of the specified parts e.g.
P:ABACABA
You can use ( )<number> to repeat a part a specified number of times
e.g. P:A(AB)6 is equivalent to P:AABABABABABAB. If there are no brackets,
just the last part is repeated, so P:AAB3 is equicalent to P:AABBB. Dots
may be inserted into the part specifier to make it easier to read
e.g P:A.AB.AC
If there is no parts specifier, the output is simply the parts (or just
the unlabelled music) in the order in which it appears in the tune body.
You may if you wish have multiple voices sounding concurrently within each
part. These are indicated by
V:1
<music for voice part 1>
V:2
<music for voice part 2>
and so on.
A part label is treated like V:1, so you are not allowed to place a part
label within a voice. The duration of each of the voice parts must be the
same for them to synchronize correctly; abc2midi will warn you if they are
not!
If no V: field appears after the K:, whatever follows is assumed to
belong to voice 1 (the default voice). The V: field is an extension to
abc 1.5.
The M:, L: Q: and K: fields in the header apply to all voices. After
the header, these fields apply only to the voice in which they appear.
Adding Lyrics to a Tune
-----------------------
The W: field (upper case W) can be used for lyrics to be typeset separately
if the abc is printed out. The w: field (lower case w) in the body of a tune
supplies a line of lyrics to be matched syllable by syllable to the last line
of notes. These are usually printed below the notes if the abc is typeset.
abc2midi uses these to generate karaoke MIDI files. When the karaoke MIDI file
is played using an appropriate player program, the lyrics appear on the screen
with the current syllable highlighted. Within the lyrics, the following
symbols may be used :
<space> break between words
- break between syllables within a word
| advance to next bar
_ indicates last syllable is to be held for another note
* indicates a one note rest for the singer.
~ appears as a space but connects syllables each side into one.
\- appears as - in the output
\ continuation character. Next w: field is part of the same line.
The following example illustrates most of these :
gf|e2dc B2A2|B2G2 E2D2|.G2.G2 GABc|d4 B2
w: Sa-ys my au-l' wan to your aul' wan\
w: Will~ye come to the Wa-x-ies dar-gle?
Note that the continuation character is used in a rather strange manner.
One w: field and all continuations will match one line of music, whether
or not the line of music ends with a continuation character. You can
think of the \ in a music line dividing that line into sections and \
in a w: field further dividing these section into sub-sections.
It is possible for a music line to be followed by several w: fields.
This can be used together with the part notation to create verses.
The first w: field is used the first time that part is played, then
the second and so on.
abc2midi-specific commands (%%MIDI)
------------------------------------
abc2midi supports a number of commands of the form
%%MIDI command
Each of these should appear on a line by itself. All of them are allowed
within the abc tune body. By using these in combination with the part
notation, one can, for example, play a part transposed or in a different key.
The idea behind this syntax is that other programs will treat it as a
comment and ignore it.
%%MIDI channel n
selects melody channel n (in the range 1-16).
%%MIDI program [c] n
selects program n (in the range 1-128) on channel c. If c is not given, the
program is selected on the current melody channel.
%%MIDI beat a b c n
controls the way note velocities are selected. The first note in a bar has
velocity a. Other "strong" notes have velocity b and all the rest have velocity
c. a, b and c must be in the range 0-128. The parameter n determines which
notes are "strong". If the time signature is x/y, then each note is given
a position number k = 0, 1, 2 .. x-1 within each bar. Note that the units for
n are not the default note length. If k is a multiple of n, then the note is
"strong". The volume specifiers !ppp! to !fff! are equivalent to the
following :
!ppp! = %%MIDI beat 30 20 10 1
!pp! = %%MIDI beat 45 35 20 1
!p! = %%MIDI beat 60 50 35 1
!mp! = %%MIDI beat 75 65 50 1
!mf! = %%MIDI beat 90 80 65 1
!f! = %%MIDI beat 105 95 80 1
!ff! = %%MIDI beat 120 110 95 1
!fff! = %%MIDI beat 127 125 110 1
%%MIDI transpose n
transposes the output by the specified number of semitones. n may be
positive or negative.
%%MIDI rtranspose n
Relative tranpose by the specified number of semitones. i.e.
%%MIDI transpose a followed by %%MIDI rtranspose b results in a
transposition of a+b. %%MIDI transpose b will result in a transposition
of b semitones, regardless of any previous transposition.
%%MIDI c n
specifies the MIDI pitch which corresponds to c. The default is 60. This
number should normally be a multiple of 12.
%%MIDI grace a/b
sets the fraction of the next note that grace notes will take up. a
must be between 1 and b-1.
%%MIDI chordname name n1 n2 n3 n4 n5 n6
Defines how to play a guitar chord called "name". n1 is usually 0 and
n2, n3 to n6 give the pitches of the other notes in semitones relative
to the root note. There may be fewer than 6 notes in the chord, but not
more.If "name" is already defined, this command re-defines it. Unlike
most other commands, chordname definitions stay in effect from where they
are defined to the end of the abc file. The following illustrates how
m, 7, m7 and maj7 could be set up if they were not already defined.
%%MIDI chordname m 0 3 7
%%MIDI chordname 7 0 4 7 10
%%MIDI chordname m7 0 3 7 10
%%MIDI chordname maj7 0 4 7 11
%%MIDI gchord string
sets up how guitar chords are generated. The string is a sequence made of
of z's, c's and f's for rests, chords and fundamental notes respectively.
This specifies how each bar is to be played. An optional length is allowed
to follow the z's, c's and f's e.g. czf2zf3. If the abc contains guitar
chords, then abc2midi automatically adds chords and
fundamentals after encountering the first guitar chord. It keeps using that
chord until a new chord is specified in the abc. Whenever the M: field is
encountered in the abc, an appropriate default string is set :
For 2/4 or 4/4 time default is equivalent to :
%%MIDI gchord fzczfzcz
For 3/4 time default is equivalent to :
%%MIDI gchord fzczcz
For 6/8 time default is equivalent to :
%%MIDI gchord fzcfzc
For 9/8 time default is equivalent to :
%%MIDI gchord fzcfzcfzc
%%MIDI chordprog n
Sets the MIDI instrument for the chords to be n.
%%MIDI bassprog n
Sets the MIDI instrument for the bass notes to be n.
%%MIDI chordvol n
Sets the volume (velocity) of the chord notes at n.
%%MIDI bassvol n
Sets the volume (velocity) of the bass notes at n. There is no corresponding
melodyvol command since there are 3 velocity values for melody, set using the
beat command.
%%MIDI gchordon
Turns on guitar chords (they are turned on by default at the start of a
tune).
%%MIDI gchordoff
Turns off guitar chords.
%%MIDI control [bass/chord] n1 n2
This generates a MIDI control event. If the word "control" is followed by
"bass" or "chord", the event will be applied to the bass or chord channel,
otherwise it will be applied to the melody channel. n1 and n2 are numbers
in the range 0-127. Generally, n1 selects a control parameter and n2 is
the value to which it is set. A couple of examples :
%%MIDI control 7 50
will set the main volume of the channel to 50
%%MIDI control 10 0
will set the pan parameter (left/right balance) to 0.
See the manual for your MIDI tone generator to find out what control events
are supported.
%%MIDI nobarlines
This is a somewhat obscure option to support early music without barlines.
Normally, an accidental applied to one note e.g. ^c will apply to every note
at the same point in the scale until the end of the bar (so C,, C, C c c'
would all be sharpened). This option turns off this behaviour, so that an
accidental applies only to the next note. It should be used in the header of
any tune requiring this behaviour.
%%MIDI barlines
This turns off the effect of %%MIDI nobarlines in the middle of a tune. This
is the default behaviour assumed at the start of every tune.
Typesetting abc
---------------
If you want to typeset your abc, there are some more features of abc syntax
that you need to know:
If 2 notes appear consecutively with no space between them, they will be
grouped together under the same beam. A space between them prevents them
sharing a beam.
A new line of stave music is generated by the newline at the end of a
line of abc music. To suppress this, put a \ character at the end of the
abc music line.
An abc music line should end either at a bar line or at the space
between two notes which indicates they do not share a beam. This is true
whether or not the abc line ends with a \ character.
Error Messages and Warnings
---------------------------
abc2midi attempts to perform various checks on the abc and
reports any problems via error and warning messages:
A warning message indicates there is something strange in the abc -
possibly an error or possibly non-standard usage.
An error message means that abc2midi thinks there is definitely an
error in the abc and the MIDI generated may not be correct.
In a small number of cases, an error may cause abc2midi to stop.
This is usually either because it has run out of memory or because
there is some problem with reading or writing a file.
---------------------------------------------------------------------
This reference written 1995-1998 by James Allwright